Stop harassing me

I am being harassed by Norman and Associates on behalf of Zone Fitness Club for the debt whose time frame of three years have lapsed. I quit Zone Fitness in November 2011, I requested to settle the outstanding amount. With 30% discount I owed just over R600.00. But the gym demanded that I pay it in full, rejected my proposal to pay that in installments. They continued to debit my account until February in 2012 as per normal contract. I was unable to pay and Zone Fitness went quiet. After the period of three years have lapsed Zone Fitness re-emerged demanding more than R4000.00 from me, with false invoice showing phone calls I never received with false duration. I kept telling Zone Fitness consultants that I can settle that amount only if it's that original amount of when I left the gym. They now harassing me through Norman and Associates and I keep telling them samwe thing over and over that I will never pay R4000.00 plus for the debt that Zone Fitness refused my settlement for. Please stop this Norman and Associates together with Zone Fitness from harassing me, three year period has lapsed. I thank you